ATP-dependent conformational dynamics in a photoactivated adenylate cyclase revealed by fluorescence spectroscopy and small-angle X-ray scattering.

Structural insights into the photoactivated adenylate cyclases can be used to develop new ways of controlling cellular cyclic adenosine monophosphate (cAMP) levels for optogenetic and other applications. In this work, we use an integrative approach that combines biophysical and structural biology methods to provide insight on the interaction of adenosine triphosphate (ATP) with the dark-adapted state of the photoactivated adenylate cyclase from the cyanobacterium Oscillatoria acuminata (OaPAC). A moderate affinity of the nucleotide for the enzyme was calculated and the thermodynamic parameters of the interaction have been obtained. Stopped-flow fluorescence spectroscopy and small-angle solution scattering have revealed significant conformational changes in the enzyme, presumably in the adenylate cyclase (AC) domain during the allosteric mechanism of ATP binding to OaPAC with small and large-scale movements observed to the best of our knowledge for the first time in the enzyme in solution upon ATP binding. These results are in line with previously reported drastic conformational changes taking place in several class III AC domains upon nucleotide binding.

How measurements of rate coefficients at low temperature increase the predictivity of photochemical models of Titan's atmosphere.

The predictivity of photochemical models of Titan's atmosphere depends strongly on the precision and accuracy of reaction rates. For many reactions, large uncertainty results from the extrapolation of rate laws to low temperatures. A few reactions have been measured directly at temperatures relevant to Titan's atmosphere. In the present study, we observed the consequences of the reduced uncertainty attributed to these reactions. The global predictivity of the model was improved, i.e., most species are predicted with lower uncertainty factors. Nevertheless, high uncertainty factors are still observed, and a new list of key reactions has been established.

Solvation dynamics of electron produced by two-photon ionization of liquid polyols. III. Glycerol.

The solvation dynamics of excess electrons in glycerol have been measured by the pump-probe femtosecond laser technique at 333 K. The electrons are produced by two-photon absorption at 263 nm. The change in the induced absorbance is followed up to 450 ps in the spectral range from 440 to 720 nm. The transient signals of electron solvation have been analyzed by two kinetic models: a stepwise mechanism and a continuous relaxation model, using a Bayesian data analysis method. The results are compared with those previously published for ethylene glycol (J. Phys. Chem. A 2006, 110, 175) and for propanediols (J. Phys. Chem. A 2007, 111, 4902). From the comparison, it is pointed out that solvation dynamics in glycerol is very fast despite its high viscosity. This is interpreted as the existence of efficient traps for the electrons in glycerol with low potential energy. The small shift of the absorption band of the excess electron indicates that the potential of these traps is very close to that corresponding to the fully solvated electron.

[Surgical management of synovial cyst of the lumbar spine: retrospective study of 52 patients]. / Prise en charge chirurgicale des kystes synoviaux lombaires: étude rétrospective concernant 52 patients.

PURPOSE OF THE STUDY: Lumbar synovial cysts are an uncommon cause of radiculopathy, low back pain and neurogenic claudication. We report a retrospective analysis of the clinical presentation, radiological studies, operative findings and outcome in 52 patients surgically treated for symptomatic lumbar synovial cysts. MATERIAL AND METHODS: Retrospective data from 52 consecutive patients treated from January 1996 to February 2006 were analyzed. We studied the clinical symptoms, diagnostic methods and radiological findings in all patients, reviewed the types of conservative therapy applied, the surgical findings and techniques, as well as the immediate and long-term results. Surgical outcomes were evaluated according to the Friedberg scale. RESULTS: There were 35 women and 17 men with an average age of 63.2 years (range 36-84 years). The most common symptoms were radiculopathy (65,4%) and neurogenic multiroot claudication (34,6%). Forty-seven patients had back pain and 22 paresthesia. Preoperative neurological examination demonstrated motor weakness (5.7%), sensory loss (7.6%). The radiological work-up consisted in CT-scan and/or MRI for all patients. The correct preoperative diagnosis was established in 44 patients. A total of 56 cysts were found. Five patients had bilateral cysts. The L4-L5 level was affected in 66%. Total resection of the synovial cyst was possible for 46 patients. No fusion was performed as a first line procedure. However, subsequent fusion was necessary in one patient who developed delayed symptomatic spondylolisthesis. Mean follow up period was 14 months ranging from six to 24 months. Three recurrences occurred during the follow-up period. Functional outcome was excellent in 61.6%, good in 34.6% and poor in 3.8%. CONCLUSION: Surgery should be proposed when synovial cysts fail to respond to conservative therapy. Recurrence and surgical complication rates are low. The usefulness of systematic fusion procedure is questionable.

[Spinal cord compression by arachnoid cysts]. / Compression médullaire par kystes arachnoïdiens.

Spinal arachnoid cysts are considered to be rare entities, intradural locations are even less common. We report two cases of patients (two women aged 77- and 21-year-old) who presented spinal cord compression by intradural arachnoid cysts. For the second patient, repeated surgical procedures were necessary to improve the neurological status. After presenting the case reports, we expose the pathophysiological mechanisms and clinical features, and the surgical difficulties of treating this rare cause of spinal cord compression.

[Thoracic and thoraco-lumbar discs herniations: diagnosis and therapeutic management]. / Les hernies discales thoraciques et thoraco-lombaires: prise en charge diagnostique et therapeutique.

Summary Management of symptomatic thoracic disc hemiations is difficult because of their polymorphic symptomatology and hardness to join the intervertebral thoracic disc surgically. The objective of this study was first to show the difficult diagnosis of these discal herniations and their posterior approach particularities; secondly, to analyse our results and compare them with those of the literature. This retrospective study analyses a four patients series operated between January 1997 and march 2003 using intraoperative somatosensory evoked potentials. All of them had before surgical management, a lumbar Xray or a MRI. The average postoperative follow-up was seven months. All patients were males with a mean age of 39.5 years old (extremes: 22-59). They had systematisation of their lumboradiculalgia, leading to an average delayed diagnosis of 10 months. The disc herniation was paramedian in three cases, median in one,. It was in T10-T11 in one case, in T11-T12 in two and in T12-L1 in one. All the patients were operated on with a posterior approach, recording the intraoperative somatosensory evoked potentials. Disc herniation was resected in three cases. Functional results were satisfactory (no pains for three patients) in the follow-up period of seven months. Every patient presenting with an atypical lumboradiculalgia must have a spine MRI to diagnose the symptomatic thoracic disc herniation. Surgery has good results if technical details are used respecting the threatened spinal cord.

Colonization of burns and the duration of hospital stay of severely burned patients.

In a retrospective study the influence of several factors on the length of hospital stay of severely burned patients (at least 24% total body surface area) has been investigated. The influence of these factors was studied by means of the Cox model survival analysis with time-varying covariates. Seventy-one patients were included in this study. The mean age was 32 years (range 1-82 years), the mean total body surface area burned 40% (range 24-80%) and the mean full-thickness area burned 32% (range 10-70%). The length of hospital stay was positively correlated with the extent of the burned area and with the age of the patient. Wound colonization with Enterobacteriaceae or with a combination of Pseudomonas spp. and Staphylococcus aureus was also associated with a prolonged stay in hospital.

[Simultaneous hepatic cholangiocarcinoma and bone fibrosarcoma 45 years after ingestion of Thorotrast]. / Cholangiocarcinome hépatique et fibrosarcome osseux synchrones 45 ans après injection de Thorotrast.

This case of a 63 year old man reports the simultaneous development of hepatic cholangiocarcinoma and fibrosarcoma of the sacrum 45 years after the systemic injection of Thorotrast. The characteristic radiologic aspect was an important criteria for diagnosis. Biopsies have confirmed the histology of both tumors. We describe the way to thorotrastosis diagnosis and characteristic malignant tumors, especially cholangiocarcinoma, induced by Thorotrast.

[Inter-apophyseal articular synovial cyst of the lumbar spine. X-ray computed tomographic and magnetic resonance imaging correlation. Apropos of 2 cases]. / Kyste synovial articulaire inter-apophysaire du rachis lombaire confrontation tomodensitométrique et imagerie par résonance magnétique. A propos de 2 cas.

Two patients presenting with L5 radiculagia were investigated by CT scan imaging. The origin of the pain was determined with certitude as arising from intraspinal development of an interapophyseal synovial cyst. Examination of the two cases by MR imaging provided conflicting results: in one patient images obtained by MR were not contributive and the synovial cyst would probably have been missed while in the other patient images were specific and very sensitive for diagnosis of interapophyseal synovial lesions. Treatment was surgical in both cases.

[Atrial septal defect type ostium secundum at the age of 40 or more. Apropos of 86 cases with hemodynamic exploration]. / CIA du type OS à l'âge de 40 ans ou plus. A propos de 86 cas explorés hémodynamiquement.

The authors propose a haemodynamic classification for ASD, taking into account the very frequent drop in systemic blood pressure which is observed in this disease in elderly people. The authors examine the clinical signs and the clinical course in terms of this haemodynamic classification and they stress the mitral abnormalities and the arrhythmias. 56% of patients were followed up for a mean of 6 years for non-operated patients and almost 10 years for operated patients. The pathophysiology of ASD is discussed. It appears to be very dependent on left ventricular function. The operation needs to be discussed in terms of the haemodynamic findings, even in elderly subjects and in almost asymptomatic subjects.

[Treatment of spondylolisthesis (stage I-II) by neurosurgical decompression without either osteosynthesis or reduction]. / Traitement du spondylolisthésis (stade I-II) par décompression neurochirurgicale sans ostéosynthèse ni réduction.

Between 1978 and 1982, 45 patients (44 adults, 1 child) with lumbar isthmic spondylolisthesis (SPL) were operated upon, through a classical posterior approach without setting or fixing. 46 SPL were at the L5-S1 level, 9 at the L4-L5, with 31 class I and 14 class II SPL, according to Meyerding. All the patients had experienced backache with radicular pain. A bilateral interlaminar way with preserving the posterior arch, allowed a large dural and radicular decompression. At the slipping level the wedge-shaped bone was removed while stripping off the disc together with its cartilaginous layer. Every possibility of root compression was cleared up: fibrosis, soft discs, osteophytic spurs, roof of the intervertebral foramina, with exploration of the adjacent levels. Neither bone graft or metallic devices were used. Apophyseal joints and their synovial membrane were denervated by coagulation. The postoperative course was uneventful. Bracing was needed for 2 months. X-ray postoperative follow-up demonstrated an important narrowing of the intervertebral space with constitution of a solid intersomatic fibrous joint without increase of slipping. Good and excellent results were obtained in 68% of cases, fair result in 20% with A 1 to 4 years follow-up. 80% of patients returned to their pre-operative occupation. After reviewing the data of the literature the authors ascertain that more complicated and sophisticated procedures do not bring out better results. They conclude that their safe and simple technique should be widely advocated for lumbar class I and II spondylolisthesis.

[Acute staphylococcal epidural inflammation. Apropos of 2 cases]. / Les épidurites staphylococciques aiguës. A propos de deux cas.

Two cases of staphylococcal infection of the epidural space are presented and on this purpose a review of literature is done to remind of this pathology and to plead for early diagnosis.

[Venous graft bypass between the subclavian artery and a cortical artery, prior to carotid ligation for giant cervical carotid aneurysm]. / Pontage avec greffon veineux entre l'artère sous-clavière et une artère corticale, prèalablement à la ligature carotidienne pour anévryseme géant carotidien cervical.

Three cases of giant aneurysm of the cervical internal carotid artery are reported. In 2 cases the aneurysm was on the left side, with a symptomatology of repeated TI A's. In 1 case the aneurysm was on the right side, with a pharyngeal symptomatology. All 3 cases were an indication of cervical internal carotid artery ligation. Prior to the carotid ligation it was thought preferable to perform an extra-intracranial arterial By-pass. The superficial temporal artery not being available, a long By-pass was performed, between the subclavian artery and a cortical artery, by means of a saphenous vein graft. In 2 cases the By-pass was angiographically patent, 11 months and 1 year postoperatively. In one case, the postoperative angiogram (3 weeks) failed to show the By-pass. The advantages and disadvantages of the procedure are discussed.

[Preservation of auditory function in the excision of acoustic neuroma]. / Conservation de l'audition dans l'exérèse des neurinomes de l'acoustique.

Selection criteria for the preservation of auditory function during excision of acoustic neurinoma have been defined for a long time, and the means for a successful achievement of such a goal are widely known. Recruitment of special patients, for whom maintenance of an even deeply altered hearing capacity constitutes a requisite for continuation of professional work has lead us to extend indications for the pre- and retrosigmoid approaches recommended by J.M. Sterkers. The authors present a series of 16 patients, in which a single case of cophosis was deplored.

[Neuronavigation in third ventricle tumors]. / Tumeurs du troisième ventricule et neuronavigation.

The authors present the results of neuronavigation as a help to open neurosurgery for the tumors of the third ventricle. From January, 1995 to August, 1999, six image-guided surgical procedures were performed to remove third ventricle lesions : 4 colloïd cysts, 1 ependymoma, and 1 craniopharyngioma. The operative approach was transcortical in 5 cases, and transcallosal in 1 case. The use of neuronavigation allows a decrease of the surgical trauma during the surgical approach. The procedure secures the neurosurgeon in the choice and execution of his pathway to the target. It becomes however less accurate after opening the ventricle, because of the brainshift induced by the loss of cerebrospinal fluid becomes important. Nevertheless, neuronavigation is useful in the surgery of the third ventricle, especially if it is used with neuroendoscopy.

[Laser microsurgery of meningioma. An analysis of a consecutive series of 164 cases treated surgically by using different lasers]. / La microchirurgie au laser des méningiomes. Analyse d'une série consécutive de 164 cas opérés avec différents lasers.

Over a six years period, 224 laser procedures were performed in our clinic, of these 164 (72%) involved meningiomas of various intracranial and spinal locations; 82 (50%) tumors were located in the posterior fossa, 36 (32%) were suprasellar or parasellar meningiomas: a carbon dioxide laser was used in 56 cases, a double wave length YAG laser in 101 cases, and recently a simultaneous Nd YAG and CO2 combolaser in 7 cases. Complete tumor removal was accomplished in 83% of cases and overall mortality was 3%. We think that microscope guided laser techniques represents a significant advancement in the ability to remove deep situated meningiomas that might prove difficult to extirpate by conventional microsurgery. The advantages of these methods include: 1. reduced brain retraction; 2. the ability to operate with smaller and different exposures; 3. a reduced amount of mechanical manipulation by vaporizing in first the dural attachment; 4. improved operative precision and 5. decreased intra operative blood loss.

[Combination of traumatic vascular and neural lesions of the limbs. Surgical approach. Apropos of 10 cases]. / Association de lésions vasculaires et nerveuses traumatiques au niveau des membres. Tactique chirurgicale. A propos de 10 cas.

Ten cases of limb injuries including vascular and nervous lesions are reported. After pointing out the modalities of diagnosis, the authors describe the surgical technic: vascular management first, and then nervous repair. After a six months to three years follow-up, among eight cases, the vascular repair is successful every time, and the nervous repair five times. Although each technic is usually easy, the association of both lesions needs the collaboration of multidisciplinary surgical teams.

On the implementation of computed laminography using synchrotron radiation.

Hard x rays from a synchrotron source are used in this implementation of computed laminography for three-dimensional (3D) imaging of flat, laterally extended objects. Due to outstanding properties of synchrotron light, high spatial resolution down to the micrometer scale can be attained, even for specimens having lateral dimensions of several decimeters. Operating either with a monochromatic or with a white synchrotron beam, the method can be optimized to attain high sensitivity or considerable inspection throughput in synchrotron user and small-batch industrial experiments. The article describes the details of experimental setups, alignment procedures, and the underlying reconstruction principles. Imaging of interconnections in flip-chip and wire-bonded devices illustrates the peculiarities of the method compared to its alternatives and demonstrates the wide application potential for the 3D inspection and quality assessment in microsystem technology.

[Recurrent giant cystic vestibular schwannomas: role of cystoperitoneal shunt]. / Schwannomes vestibulaires kystiques géants: intérêt du drainage kystopéritonéal.

INTRODUCTION: Surgical removal of giant cystic vestibular schwannomas is difficult because of adherences between the cyst membrane, brainstem, and the VII-VIII nerve complex. The recurrence of the cyst is frequent and requires reoperation. The aim of this study was to analyze the role of the palliative cystoperitoneal shunt in giant cystic vestibular schwannomas. MATERIALS AND METHODS: Eighty-eight patients with a diagnosis of stage III or IV vestibular schwannoma were managed surgically from January 2000 to December 2005 in our department. Six schwannomas were deemed to be cystic according to the following criteria: a voluminous cystic component with mass effect causing symptoms as well as radiological and intraoperative identification of cystic elements. RESULTS: Complete tumor removal was achieved in two patients. After a follow-up of 5 and 7 years, these patients were asymptomatic. In four cases, we performed cyst drainage. For three patients, we implanted a permanent cystoperitoneal shunt. These patients were asymptomatic with a mean follow-up of 19.7 months. CONCLUSIONS: The cystoperitoneal shunt with no valve is a valid palliative surgical solution to remove brain stem compression. Neuronavigation allows proper positioning of the drain and secures the procedure.